21230809 has 8 divisors (see below), whose sum is σ = 22655840. Its totient is φ = 19836576.

The previous prime is 21230801. The next prime is 21230827. The reversal of 21230809 is 90803212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21230809 - 2³ = 21230801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21230801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6267 + ... + 9040.

It is an arithmetic number, because the mean of its divisors is an integer number (2831980).

Almost surely, 2^21230809 is an apocalyptic number.

It is an amenable number.

21230809 is a deficient number, since it is larger than the sum of its proper divisors (1425031).

21230809 is a wasteful number, since it uses less digits than its factorization.

21230809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15399.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21230809 is about 4607.6902022597. The cubic root of 21230809 is about 276.8995060917.

The spelling of 21230809 in words is "twenty-one million, two hundred thirty thousand, eight hundred nine".